Thanks Nick - I've had my working too.
I was wondering if the last link in the chain (Explorer 2) worked as well.

Main: G61SL, 218, HD621, 2*7200SE, 7200HCSE, M6s, DSW, Apple TV 4K, NUC (Roon server)
Secondary: Wiim Pro, 3200, Audio Core 200
F80